A321800 Delete the decimal digits of n that appear exactly once; write -1 if all digits disappear.

-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 22, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 33, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 44, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 55, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 66, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 77, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 88, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 99, 0, 11, -1, -1, -1, -1, -1, -1, -1, -1, 11, 111, 11, 11, 11, 11, 11, 11, 11, 11, -1, 11, 22, -1, -1, -1, -1, -1, -1, -1, -1, 11, -1, 33, -1, -1, -1, -1, -1, -1, -1, 11, -1, -1, 44, -1, -1, -1, -1, -1, -1, 11, -1, -1, -1, 55, -1, -1, -1, -1, -1, 11, -1, -1, -1, -1, 66, -1, -1, -1, -1, 11, -1, -1, -1, -1, -1, 77, -1, -1, -1, 11, -1, -1, -1, -1, -1, -1, 88, -1, -1, 11, -1, -1, -1, -1, -1, -1, -1, 99

Offset

0,12

Comments

A companion sequence to A320485.

Digits that appear exactly once in n are erased. Leading zeros are erased unless the result is 0. If all digits are erased, we write -1 for the result (A321797 is another version, which uses 0 for the empty string).

More than the usual number of terms are shown in order to reach some interesting examples.

Links

Chai Wah Wu, Table of n, a(n) for n = 0..10000

Example

12321 becomes 1221, 1123 becomes 11, 11231 becomes 111, and 100223 becomes 22 (as we don't accept leading zeros). Note that 12345 disappears immediately and we get -1.

Prog

(Python)
def A321800(n):
    return (lambda x: int(x) if x != '' else -1)(''.join(d if str(n).count(d) != 1 else '' for d in str(n)))

Crossrefs

Cf. A320485, A321797.

Sequence in context: A109014 A268357 A321804 * A130837 A010194 A280443

Adjacent sequences: A321797 A321798 A321799 * A321801 A321802 A321803

Keyword

sign,base,look

Author

Chai Wah Wu, Nov 19 2018

Status

approved